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<html>
<h2>Combine - BinaryCombineFn Lambda</h2>
<p>
  BinaryCombineFn is used for implementing combiners that are more easily expressed as binary
  operations.
</p>
<p>
  Since Beam v2.13.0, you can also use lambda or method reference in order to create the
  BinaryCombineFn.
</p>
<p>
  <b>Kata:</b> Implement the summation of BigInteger using lambda or method reference.
</p>
<br>
<div class="hint">
  Refer to
  <a href="https://beam.apache.org/releases/javadoc/current/org/apache/beam/sdk/transforms/SerializableBiFunction.html">
    SerializableBiFunction</a>.
</div>
<div class="hint">
  Refer to the Beam Programming Guide
  <a href="https://beam.apache.org/documentation/programming-guide/#combine">
    "Combine"</a> section for more information.
</div>
</html>
